Epidemiology and Evolution of Invasive Pneumococcal Disease Caused by Multidrug Resistant Serotypes of 19A in the 8 Years After Implementation of Pneumococcal Conjugate Vaccine Immunization in Dallas, Texas
ABSTRACT The heptavalent pneumococcal conjugate vaccine (PCV7) has significantly reduced vaccine-type invasive pneumococcal disease (IPD) in children. An increasing percentage of IPD cases are now caused by nonvaccine serotypes. The purpose of our observational study was to define the epidemiology of pneumococcal disease in Dallas, TX children for 8 years after implementation of PCV7 immunization.
Streptococcus pneumoniae isolates from normally sterile sites were collected at Children's Medical Center of Dallas from January 1, 1999 to December 31, 2008. Incidence of IPD was calculated using inpatient and emergency center admissions to Children's Medical Center of Dallas as the denominator. Isolates were serotyped and penicillin and cefotaxime susceptibilities were determined. Serotype 19A isolates were further characterized by multilocus sequence typing.
Compared with the prevaccine period of 1999-2000, there was a significant reduction in the incidence of IPD from 2002 to 2008 (P < 0.05), although a significant increase in IPD incidence was observed from 2006 to 2008 (P = 0.038). The number of IPD cases caused by serotype 19A increased from 1999 to 2008 (P < 0.001). There were significant increases in penicillin and cefotaxime nonsusceptible 19A isolates during this 10-year period (P < 0.001 and P = 0.004, respectively). The most common sequence type (ST) of the 19A isolates was ST-199 (42.7%). Clonal complex (cc-156) and cc-320 emerged in the period of 2005-2008 as penicillin and cefotaxime resistant 19A strains.
In Dallas, PCV7 immunization reduced significantly the incidence of IPD caused by vaccine-type strains. A significant increase in IPD caused by serotype 19A was observed. The penicillin and cefotaxime nonsusceptible STs, not previously identified in Dallas, have recently become an important cause of IPD.
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ABSTRACT: Acute otitis media is among the most common reasons young children seek medical care, with Streptococcus pneumoniae the most common pathogen. Despite introduction of heptavalent pneumococcal conjugate vaccine (PCV7) in 2000, recent experience suggests an increase in complications of acute otitis media, particularly acute mastoiditis. We performed a retrospective review of acute mastoiditis in children from 1999 to 2008 using inpatient data from the Colorado Hospital Association and the Children's Hospital Colorado. The study included patients with documentation of acute mastoiditis or mastoidectomy and excluded those with chronic mastoiditis, chronic otitis media or cholesteatoma. The annual incidence of acute mastoiditis in children <2 years/100,000 population was 11.0 in 2001 before decreasing to 4.6 in 2002 and 4.5 in 2003. The incidence then increased to 12.0 in 2008 (total N = 242). The proportion of S. pneumoniae isolates nonsusceptible to penicillin increased from 0% (0/16) between 1999 and 2004 to 38% (5/13) between 2005 and 2008 (P = 0.03). The incidence of acute mastoiditis in Colorado children <2 years of age exhibited a dynamic pattern from 1999 to 2008: a significant decline early after introduction of PCV7 that paralleled initial vaccine uptake, followed by an increase in subsequent years to pre-PCV7 levels. Replacement with non-PCV7 pneumococcal serotypes and increased pneumococcal antibiotic resistance may be responsible for the increase in incidence to pre-PCV7 rates. Surveillance of mastoiditis incidence, pathogen distribution and resistance patterns following introduction of 13-valent PCV is warranted.The Pediatric Infectious Disease Journal 05/2014; 33(5):453-7. DOI:10.1097/INF.0000000000000138 · 3.14 Impact Factor
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ABSTRACT: Dissemination of antibiotic resistant clones is recognized as an important factor in the emergence and prevalence of resistance in pneumococcus. This study was undertaken to survey the antimicrobial susceptibility and serotypes distribution of pneumococci and to explore the circulating clones in hospitalized children in Suzhou, China. The pneumococci were isolated from the nasopharyngeal aspirates of children less than 5 years of age admitted to Soochow-University-Affiliated-Children's-Hospital with respiratory infections. The capsular serotypes were identified by multiplex polymerase chain reaction (PCR). Antimicrobial susceptibility was tested by E-test. The presence of ermB, mefA/E genes were detected by PCR and the genotypes were explored by Multilocus sequence typing (MLST). From July 2012 to July 2013, a total of 175 pneumococcal isolates were collected and all strains were resistant to erythromycin and clindamycin, about 39.4% strains were non-susceptible to penicillin G. Overall, 174 (99.4%) isolates were resistant to ≥3 types of antibiotics. Serotypes 19F (28.1%), 6B (19.7%), 19A (18.0%), and 23F (17.4%) were the most common serotypes in all identified strains. The serotypes coverage of PCV7 and PCV13 were 71.9% and 89.9%, respectively. Four international antibiotic-resistant clones, including Taiwan19F-14 (n = 79), Spain23F-1(n = 25), Taiwan23F-15(n = 7) and Spain6B-2(n = 7), were identified. The Taiwan19F-14 clones have a higher non-susceptibility rate in β-lactams than other clones and non-clone isolates (p<0.001). In addition, 98.7% Taiwan19F-14 clones were positive of both ermB and mefA/E genes, compare to 33.3% in other clones and non-clone strains. The spread of international antibiotic-resistant clones, especially Taiwan19F-14 clones, played a predominant role in the dissemination of antimicrobial resistant isolates in Suzhou, China. Considering the high prevalence of PCV7 serotypes and serotype 19A, the introduction of PCV13 may be a promising preventive strategy to control the increasing trend of clonal spread in China.PLoS ONE 04/2014; 9(4):e93752. DOI:10.1371/journal.pone.0093752 · 3.53 Impact Factor